Previously, the LCD code needed to be aware of each synthesizer to know
how to draw their respective displays, which wasn't very maintainable.
Introduce a UI class where generic drawing utility functions and
"system" drawing code can be implemented, and move synth-specific
drawing to the synth classes themselves. This simplifies the LCD/OLED
drivers to just being interfaces to the hardware.
Also introduce a "MIDI monitor" class which tracks the state of all MIDI
activity per-synth for level meter drawing purposes. This ensures we
never miss a note; previously we were simply polling each synth engine
for its note velocities per LCD update, which was prone to missing fast
notes and also didn't account for channel volume or expression pedal.
Finally, enable support for 16-character wide displays (closes#58).
This commit adds a simple physical control system with two schemes:
* simple_buttons: 4-button scheme
* simple_encoder: 2-button scheme + rotary encoder (with button)
This commit adds a driver for the Blokas Pisound audio/MIDI HAT based on
the Linux sources.
Currently this requires a patch to Circle to allow the Pi's I2S audio
device to operate in slave mode.
The Pisound only works at 48000Hz, 96000Hz, and 192000Hz. The Pisound is
automatically detected by the startup code; the user only has to enable
I2S audio output.
MIDI output and recording functionality is not supported.
Closes#42.
A hang could occur when using a USB MIDI interface in SoundFont mode, or
when resuming from power saving mode.
The USB MIDI interrupt handler now enqueues MIDI data into a circular
buffer that is then read from the main task context to ensure thread
safety.
Improve status/error logging on the LCD.
Also fix clearing the screen on reboot by moving the call to Clear() to
the UI core and waiting for the UI core to be done before rebooting.
Refactor synth code to decouple it from the audio driver and instead use
the drivers' Write() methods to insert rendered audio into a queue from
CPU core 2.
